There are numerous disclosures in the art as to the desirability of fueling an internal combustion engine (ICE) with hydrogen. Not the least among the advantages envisioned by the art is that a hydrogen fueled ICE should produce only water as an exhaust product rather than the water-carbon oxide exhaust products of engines fueled by hydrocarbons. The absence of carbon oxides especially carbon monoxide from exhaust gases is very important in instances where the ICE is employed in closed-off spaces such as in mines. Buildup of carbon monoxide in mine atmospheres is exceedingly dangerous and is the subject of mine safety regulation. Where ICE's fueled by hydrocarbons are employed in mines, it is mandatory that excess ventilation be provided so as to prevent exhaust fume buildup. Such excess ventilation is costly not only in capital equipment but also in operation and maintenance. In addition to usage in mines and other enclosed spaces, it is envisioned that hydrogen-fueled ICE's may find uses based upon the premise that hydrocarbon fuels are becoming scarce and more expensive. For example, it is contemplated that hydrogen can become an economically and environmentally acceptable fuel for urban busses and autos, fork-lift trucks and other vehicles used in circumstances where exhaust fumes are a problem.
Fueling an ICE with hydrogen presents problems. Substantial testing has revealed that hydrogen cannot be reliably introduced into an ICE by carburetion, that is by premixing air or other oxidizer and hydrogen and introducing the mixture into the combustion volume or volumes (e.g. cylinder or cylinders) of an ICE. Even if a carbureting device is employed to provide a properly stoichiometrically lean, hydrogen to air mixture, occasional instances of prefiring in the carburetor occur. Prior known fuel injection systems proposed for hydrogen fueling of ICE's are sometimes of complicated and expensive design and/or rely upon precise, difficultly maintainable valve settings to deliver controllable amounts of hydrogen to combustion volumes so as to provide adequate operator control of the ICE. Some prior systems, in effect, require an operator with an "educated foot", i.e. skill beyond that of an ordinary person, to produce satisfactory engine operation.
Some of the factors which must be considered in fueling an ICE with hydrogen are low volume energy density of the gas at low pressures; the fact that a hydrogen fueled ICE must be run lean, for example between about 20% and 70% stoichiometric with respect to hydrogen (i.e., between about 0.2 and 0.7 fuel/air equivalence ratio) so as to avoid excess nitrogen oxide (NO.sub.x) emissions and abnormal combustion and; the fuel source should be at a pressure which does not present a serious hazard in case of accident. These and other factors and difficulties must be considered in any proposal for fueling an ICE with hydrogen.